Such a travelling cleaner is known in its basic construction from DE-B-16 85 860. It has a blowing and sucking device, with which fibers, yarn remains and similar residues can be blown off the textile machines and then sucked up. In a filter device, these residues are separated from the transporting air. The filter may be in the form of a filter mat.
In practice, it is also known to install tubular filter cartridges in such travelling cleaners. The filter is connected via an air connection to the blowing and sucking device, so that cleaned air is available for the blowing off of the residues. In the case of the known filter cartridges, the air connection is situated on the end face, whereby the contaminated air flows axially into the cartridge and leaves radially through the filter casing. The known arrangement has problems with the multiple air deflections in the blowing and sucking device and also in the filter and with the effectiveness of the filter device. In addition, this arrangement makes it difficult to clean the filter cartridge. The yarn finish and size cause the filters to clog relatively readily, which leads to short filter service lives and leads to frequent maintenance and cleaning of the filter.
DE-A-26 25 559 and DE-A-22 21 117 show travelling cleaners with drum filters, which are subjected to negative pressure by an internal suction connection. The air flows through the filter casing radially from outside into the drum and leaves again axially.
For cleaning the soiled filter, filter-cleaning apparatuses are used. Such an apparatus is known from DE-B-16 85 860. It has a suction-removal device which can be docked on the filter chamber and with which it is intended to suck off and remove the residues from the flat filter. To depressurize the filter in this case, an additional shutter underneath the filter is opened, via which shutter the fan of the cleaning apparatus can take in secondary air.
Instead of suction removal, it is also known from DE-B-16 85 870 to blow out a flat filter in counter-air flow into a collecting chamber. The counter-air is generated by a reversing of the fan or a changing of its direction of flow by means of shutter control. There is no separate suction-removal device here. In addition, the fan of the cleaning apparatus is used for cleaning the filter. The mechanics required are complex, susceptible to faults and complicated in both citations.
DE-A-43 21 869 shows a different filter-cleaning apparatus. The blowing device of the travelling cleaner takes in ambient air via a drum filter which is rotatingly mounted and driven. The filter-cleaning apparatus has a blowing device and a suction-removal device, which are arranged on opposite sides of the filter and together clean the filter with a counter-flow flushing. The blowing device of the filter-cleaning apparatus is fed by the fan of the travelling cleaner and has no pressure generator of its own. The filter-cleaning apparatus operates with relatively low blowing and sucking pressures, which are aimed at providing low pressures and approximately equal volumetric flows. The blowing and sucking nozzles of the cleaning apparatus are directed in the same direction. The filter serves only for cleaning the ambient air taken in for the blowing operation, which is laden relatively little with fiber fluff and other contaminants. Therefore, low blowing and sucking pressures and low flow rates suffice for filter cleaning. The much more contaminated suction-removal air, which the cleaning apparatus sucks off the factory floor and off the textile machines, is not passed over the said but is diverted directly into the fixed suction duct and is passed there to the external disposal device.
DE-A-36 29 559 discloses a further filter cleaning apparatus, which is referred to there as a dust extracting apparatus. The filter is funnel-shaped and is cleaned by stationary blowing nozzles arranged in the form of a ring at the inlet point. The blowing air swept along the filter walls in parallel is intended to detach the filter residues and take them along into a collecting shaft with depository. The cleaning apparatus is shut down during the filter-cleaning operation. For the filter cleaning, only a superficial blowing off or stripping off of the filter residues takes place, but no counterflushing of the filter walls.
DE-B-12 59 545 shows a similar filter-cleaning apparatus. The filter residues are blown off with compressed air along the plate-shaped filter and, if appropriate, sucked off with the same operative direction. Here too, no counter-flushing of the filter takes place. Rather, the clean-air side of the cleaning apparatus is closed by shutters.
DE-B-12 30 538 discloses a stationary filter-cleaning apparatus which comprises a receiving container with a blowing device, into which container the filter box or collecting container of a travelling cleaner can enter. The collecting box for the filter residues has a closeable shutter, which permits emptying. Fitted on the upper side of the collecting box is a flat filter. This is counter-flushed by compressed air by the blowing device of the filter-cleaning apparatus on entering into the receiving box. There is no sucking device operating together with the blowing device.
In practice, the effectiveness of the known filter-cleaning apparatuses has proved to be inadequate. The yarn finish and size lead to the filter being clogged by the residues and make their removal more difficult. The known suction-removal device often cannot detach the residues. The alternative blowing out of the filter has, on the other hand, the disadvantage that the residues are swirled in the collecting chamber and blown out again into the ambience. As a result, the cleaning effect on the textile machine is at least partially negated again. Although a reduction in the blowing intensity alleviates this disadvantage, on the other hand it has the consequence again of a reduced detachment of the residues from the filter. The result is that the known techniques lead to short filter service lives and cause frequent maintenance and exchanging of the filter.